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NEETPhysicsDual Nature of Matter

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): If the distance of a point source of monochromatic light from a photoelectric metal surface is doubled, the stopping potential of the emitted photoelectrons remains unchanged. Reason (R): The stopping potential depends only on the frequency of incident light and the nature of the material, and is i

Options

  1. ABoth (A) and (R) are true and (R) is the correct explanation of (A)
  2. BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
  3. C(A) is true but (R) is false
  4. D(A) is false but (R) is true

Correct answer

A. Both (A) and (R) are true and (R) is the correct explanation of (A)

Step-by-step solution

For a point source of light, the intensity I at a distance r follows the inverse square law ( I 1 r^2 ). When the distance is doubled, the intensity of the light falling on the metal surface becomes one-fourth of its initial value. However, the frequency of the incident monochromatic light remains unchanged. According to Einstein's photoelectric equation, the maximum kinetic energy and hence the stopping potential ( V₀ = h - ₀ e ) depend only on the frequency of the incident light and the work function of the mater

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